1. Field of Invention
The invention relates to a circuit board and, more particularly, to a circuit hoard with a telecommunication network connection port.
2. Related Art
With the development of the science and technology, the electronic device is developed toward integration and minimization. The size of the circuit board of the electronic device is reduced, and many function modules such as a circuit board module having a function of modem card should be integrated.
As shown in FIG. 1, taking a conventional motherboard 1 as example, the motherboard 1 includes a telecommunication network connection port 11, a modem card processing module 12 and a signal connection wire 13. The telecommunication network connection port 11 and the modem card processing module 12 are disposed at the surface of a circuit board 10. A telecommunication network plug (not shown) connected to the telecommunication network voltage (TNV) circuit may be inserted into the telecommunication network connection port 11. The signal connection wire 13 is electrically connected to the telecommunication network connection port 11 and the modem card processing module 12, and therefore, the modem card processing module 12 may communicate with the TNV circuit.
The circuit board 10 includes a plurality of conductive layers, and a plurality of signal lines are laid out at each conductive layer, respectively. The external signal connection wire 13 is connected to the telecommunication network connection port 11. The modem card processing module 12 may be fixed on a circuit board. Since the quality of the early modem card processing module 12 is unstable, the modem card processing module 12 is usually fixed on the circuit board in a locking mode to be repaired and replaced conveniently.
In addition, the TNV of each country is different, and some TNV is hazardous voltage whose peak value exceeds forty-two volts called high voltage signal instead of safety extra-low voltage. Some signals transmitted by the telecommunication network connection port 11 are high voltage signals. As a result, to prevent the signal connection wire 13 transmitting the high voltage signals from interfering with the low voltage signal line laid out on the circuit board, the signal connection wire 13 is coated with insulating material, and an iron core 14 is jacketed on the signal connection wire 13. The problem that the lines have electromagnetic radiation interference (EMI) because of the wiring passing the high speed line signal area and the high frequency noise coupled to the connection wire is solved. However, the wire and insulated material of the signal connection wire 13 and the iron core 14 increase the manufacture cost of the circuit board 10. The modem card processing module 12 is fixed it the motherboard in a locking mode, which also costs the manufacture cost.